Method for preparing 3-thionphene ethyl formate compound
A technology of ethyl thiophene formate and ethyl chloroformate is applied in the field of preparation of ethyl 3-thiophene formate compounds, and can solve the problem that n-butyllithium and thionyl chloride are expensive, unsuitable for industrial production, and have many reaction steps, etc. problem, to achieve the effect of low cost, high yield and few preparation steps
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Embodiment 1
[0049] Preparation of ethyl 2,4-dimethyl-3-thiophenecarboxylate
[0050] Add 3.4 g of catalyst cuprous iodide (analytical pure) to 38.8 g of 2,4-dimethyl-3-thiophene magnesium bromide Grignard reagent at -20°C, stir for 20 minutes, then add analytical pure ethyl chloroformate dropwise 25.7 mL of the ester in 100 mL of anhydrous tetrahydrofuran solution, the temperature was controlled at 0°C, after the dropwise addition was completed, it was stirred at below 0°C for 3 hours, and then naturally rose to room temperature. After the reaction was completed, the reaction solution was slowly added to 250 mL of saturated ammonium chloride aqueous solution under an ice-water bath, stirred for 30 min, allowed to stand for stratification, and the aqueous layer was extracted twice with 200 mL of dichloromethane. The organic phases were combined and washed with saturated saline solution for 2 time, then washed with water once, dried with anhydrous sodium sulfate, concentrated the organic ph...
Embodiment 2
[0052] Preparation of ethyl 3-thiophenecarboxylate
[0053] (1) Preparation of 3-thiophene magnesium bromide Grignard reagent
[0054] Replace the reaction bottle with an inert gas atmosphere, add 5.1 g of magnesium chips and anhydrous tetrahydrofuran solution (just enough to cover the magnesium chips) into the reaction bottle, start mechanical stirring, and add analytically pure 3-bromothiophene into the reaction bottle at room temperature 25g of anhydrous tetrahydrofuran solution 60mL, first add 6mL dropwise, then add 0.1mL analytically pure methyl iodide, after triggering the Grignard reaction later, add dropwise the remaining anhydrous THF solution of 3-bromothiophene, the temperature is maintained at 50°C After the dropwise addition, stir at 45°C for 4h to obtain 3-thiophene magnesium bromide Grignard reagent.
[0055] (2) Preparation of ethyl 3-thiophenecarboxylate
[0056] At -20°C, add 2.2 g of catalyst cuprous bromide (analytical pure) to the Grignard reagent prepar...
Embodiment 3
[0058] Preparation of ethyl 2-methyl-3-thiophenecarboxylate
[0059] (1) Preparation of 2-methyl-3-thiophene magnesium bromide Grignard reagent
[0060] Replace the reaction bottle with an inert gas atmosphere, add 10 g of magnesium chips and anhydrous tetrahydrofuran solution (just enough to cover the magnesium chips) into the reaction bottle, start the mechanical stirring, and add analytically pure 2-methyl- 52.3g of 3-bromothiophene in 140mL of anhydrous tetrahydrofuran solution, first add 14mL dropwise, then add 0.5mL of analytically pure methyl iodide, and after the Grignard reaction is triggered later, add dropwise the remaining 2-methyl-3-bromothiophene Anhydrous tetrahydrofuran solution, the temperature is maintained at about 45°C, after the dropwise addition is completed, it is stirred at 40°C for 4 hours to obtain 2-methyl-3-thiophene magnesium bromide Grignard reagent.
[0061] (2) Preparation of ethyl 2-methyl-3-thiophenecarboxylate
[0062] At -20°C, add 4.2 g o...
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